Fully fluorinated polymers

Perfhioroalko] (Teflon) (PFA) was introduced in 1972 and is a fully fluorinated polymer that is melt-processible with better melt flow and molding properties than the FEP. The PFA has excellent resistance to chemicals. It can withstand acids as well as caustic materials. PFA has better mechanical properties than FEP above 300°F (149°C) and can be used up to 500°F (260°C) for some applications. The low physical strength and high cost of this polymer limit use for some applications. 

It possesses outstanding barrier properties to gases, especially water vapor. It is surpassed only by the fully fluorinated polymers in chemical resistance. A few solvents dissolve it at temperatures... 

As was noted above, functional fluoropolymers produced by copolymerization of fluoroolefins with functional PFAVE have several unique properties, with the main disadvantage of these materials being the extremely high cost of functional monomers and the resulting high cost of the functional polymers produced from them. The fact that they are so expensive limits their wider industrial application in other fields such as catalysis and membrane separation, except for chlorine-alkali electrolysis and fuel cells, where the only suitable materials are fully fluorinated polymers because of the extreme conditions associated with those processes. 

Fluoropolymers also low flammability. The fully fluorinated polymer polytetrafluoroethylene, for example, burns only in 95% oxygen under the test conditions of LOI. The burning, however, produces a highly toxic and corrosive gas hydrogen fluoride. 

Perfluoralkoxy is a fully fluorinated polymer having the following formula ... 

Polytetrafluoroethylene (PTFE) is a fully fluorinated polymer, which was discovered by chance in 1938 by Roy Plunkett. Later, the polymerization process was initiated at high pressure with peroxide. In 1941, DuPont received the patent on PTFE, therefore it is often denoted colloquially by Teflon , the original trade name of DuPont PTFE (ref DuPont). Other examples of PTFE trade names used by manufacturers are PTFE Dyneon , formerly ffostaflon (ret Dyneon), and Gore-Tex (ret Gore). 

The fully fluorinated polymers, that is, polytetrafluoroethylene (PTFE) and the copolymer of tetrafluoroethylene and hexafluoroethylene (FEP) are difficult to adhere to and, to obtain satisfactory adhesion, it is usually necessary to pre-treat these polymers. With partially fluorinated polymers, it is often possible to obtain good adhesion without a pre-treatment for example, good bond strengths have been obtained with poly(vinyl fluoride) and poly(vinylidene fluoride) and polychlorotrifluoroethylene and the copolymer of chlorotrifluoroethylene and vinyl fluoride. ... 

The wide range of pre-treatments for fully fluorinated polymers has been reviewed by Dahm. The methods available include the following ... 

Poly(hexafluoropropylene-co-vinylidene fluoride) n. 1,1,2,3,3,3-hexafluoro-l-propene-co-l,l-difluoroethene a fully fluorinated polymer based on gas CF3 CF=CF2, not commercial. However, the co-polymers of hexafluoropropylene and tetrafluoroethylene make up the family of fluorinated ethylene propylene resins (See image). 

Fully Fluorinated Polymers. The radiation chemistry of fully fluorinated polymers shows remarkable temperature dependence, with all of the fluorinated thermoplastics undergoing degradation, ie, chain scission, at ambient temperatures, but with an increasing yield of cross-linking reactions at elevated temperatures. Over the past 10 years, this has led to renewed interest in the radiation chemistry and applications of these materials (see Perfluorinated Polymers, Polytetrafluoroethylene). 

Surface modification of the polymeric membranes via molecular design is one of the most versatile means to improve the surface properties without affecting bulk properties. Surface modification of fluoropolymer membranes, especially for fully fluorinated polymer membranes, such as PTFE membranes, has been of particular interest, due to their physical and chemical inertness. Surface modification of fluoropolymer membranes can be classified into two categories surface coating and surface grafting. 

PEM fuel cells use a solid polymer membrane (a thin plastic film) as the electrolyte. The standard electrolyte material currently used in PEM fuel cells is a fully fluorinated Teflon-based material produced by DuPont for space applications in the 1960s. The DuPont electrolytes have the generic brand name Nafion, and the types used most frequently are 113, 115, and 117 [13, 57-62,68]. The Nafion membranes are fully fluorinated polymers that have very high chemical and thermal stability. This polymer is permeable to protons when it is saturated with water, but it does not conduct electrons. 

One of the disadvantages of PTIE is that it is not melt processable. In 1960 DuPont introduced fluorinated ethylene propylene (FEP), which was chiefly designed to provide melt processability. In 1972 DuPont introduced another fully fluorinated polymer, perfluoroalkoxy (PEA), which is also melt processable, with better melt flow and molding properties than FEP. Although PEA has somewhat better physical and mechanical properties than FEP above 3000°F (1490°C), it lacks the physical strength of PTFE at elevated temperatures and must be reinforced or designed with thickness to compensate for its softness. The heat deflechon temperature of PFA is the lowest of all fluoropolymers. PFA is used to make tubing products. 

Ethylene chloro-trifluoroethylene (ECTFE) is a partially fluorinated melt processable polymer that is intermediate in performance between fully fluorinated polymers (PTFE) and PVDF. It has excellent chemical resistance to oxidizing chemicals and is used in chemical piping apphcahons for severe environments. 

Ethylene Tetrafluoroethylene Copolymer - Thermoplastic comprised of an alternating copolymer of ethylene and tetrafluoroethylene. Has high impact resistance and good abrasion resistance, chemical resistance, weatherability, and electrical properties approaching those of fully fluorinated polymers. Retains mechanical properties from cryogenic temperatures to 356°F. Can be molded, extruded, and powder-coated. Used in tubing, cable and wire products, valves, pump parts, wraps, and tower packing in aerospace and chemical equipment applications. Also called ATFA. 

PTFE is a fully fluorinated polymer which is bioinert. Preclude (Gore-Tex, W.L. Gore Associates) is expanded PTFE (ePTFE) non-absorbable permanent membrane. For adhesion prevention, fairly large pieces are needed, and they must be sutured into place as it does not adhere to tissue. Clinical studies have exhibited the effectiveness of this PTFE product [124, 125]. However, adhesion on suture lines and foreign-body reaction due to their prolonged presence make it not preferred. This product was discontinued by the manufacturer since 2011. 

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